Assertion: Reduction of nitrogen to ammonia by living organisms is called nitrification.
Reason: Example of free-living nitrogen fixing anaerobic microbes are Azotobacter and Bijerinckia.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. if both assertion and reason are true but reason is not the correct explanation of assertion
C. if assertion is true but reason is false
D. if both assertion and reason are false

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states: "Reduction of nitrogen to ammonia by living organisms is called nitrification."

- **Analysis**: This statement is incorrect. The process of reducing nitrogen gas (N2) to ammonia (NH3) is known as **biological nitrogen fixation**, not nitrification. Nitrification refers to the conversion of ammonia into nitrites (NO2-) and then into nitrates (NO3-).

### Step 2: Understand the Reason
The reason states: "Example of free-living nitrogen-fixing anaerobic microbes are Azotobacter and Bijerinckia."

- **Analysis**: This statement is also incorrect. Azotobacter and Bijerinckia are indeed free-living nitrogen-fixing bacteria, but they are **aerobic**, not anaerobic. Anaerobic bacteria do not require oxygen, while Azotobacter and Bijerinckia thrive in the presence of oxygen.

### Step 3: Conclusion
Since both the assertion and the reason are false, we can conclude that:

- **Final Answer**: Both assertion and reason are false.